Fair Value Measurements Nonrecurring Measurements (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of equity-method investments		$ 0	$ 0		$ 0	$ 112
Impairment of certain assets		25	802		26	810
Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Disposal Group, Not Discontinued Operation, Loss (Gain) on writedown						341
Williams Partners [Member] | Delaware Basin Gas Gathering System [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of equity-method investments						59
Impairment Of Certain Assets [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets					26	810
Fair Value, Measurements, Nonrecurring [Member] | Impairment Of Certain Assets [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets	[1]				3	15
Fair Value, Measurements, Nonrecurring [Member] | Impairment Of Equity-Method Investments [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of equity-method investments						112
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Property Plant And Equipment, net [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair Value of Property, Plant, and Equipment	[2]		18			18
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Property Plant And Equipment, net [Member] | Other [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair Value of Property, Plant, and Equipment	[3]	18			18
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Assets Held For Sale [Member] | Williams Partners [Member] | Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Assets Held-for-sale, Long-Lived, Fair Value Disclosure	[4]		924			924
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Assets Held For Sale [Member] | Other [Member] | Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Assets Held-for-sale, Long-Lived, Fair Value Disclosure	[4]		206			206
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair value of investment				$ 0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Fair value of investment	[5]			$ 1,294
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member] | Williams Partners [Member] | Minimum [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Discount rate				13.00%
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Investments [Member] | Williams Partners [Member] | Maximum [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Discount rate				13.30%
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets					$ 23	$ 795
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets	[2]		48
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Williams Partners [Member] | Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Disposal Group, Not Discontinued Operation, Loss (Gain) on writedown	[4]		341
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Other [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of certain assets	[3]	$ 23
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Certain Assets [Member] | Other [Member] | Canadian Operations [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Disposal Group, Not Discontinued Operation, Loss (Gain) on writedown	[4]		$ 406
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Equity-Method Investments [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of equity-method investments				$ 3
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Equity-Method Investments [Member] | Williams Partners [Member]
Fair Value Assets Measured On Nonrecurring Basis [Abstract]
Impairment of equity-method investments	[5]			$ 109

[1] Reflects multiple individually insignificant impairments and write-downs of other certain assets that may no longer be in use or are surplus in nature for which the fair value was determined to be zero or an insignificant salvage value.

[2] Relates to certain gathering assets within the Mid-Continent region. The estimated fair value was determined by a market approach based on our analysis of observable inputs in the principal market.

[3] Relates primarily to project development costs associated with an olefins pipeline project in the Gulf Coast region, the likelihood of completion of which is now considered remote. The estimated fair value of the remaining pipe and equipment considered a market approach based on our analysis of observable inputs in the principal market, as well as an estimate of replacement cost.

[4] Relates to our Canadian operations. We designated these operations as held for sale as of June 30, 2016. As a result, we measured the fair value of the disposal group, resulting in an impairment charge. The estimated fair value was determined by a market approach based primarily on inputs received in the marketing process and reflected our estimate of the potential assumed proceeds. We disposed of our Canadian operations through a sale during the third quarter of 2016.

[5] Relates to Williams Partners’ previously owned interest in DBJV and current equity-method investment in Laurel Mountain. Our carrying values in these equity-method investments had been written down to fair value at December 31, 2015. Our first-quarter 2016 analysis reflected higher discount rates for both of these equity-method investments, along with lower natural gas prices for Laurel Mountain. We estimated the fair value of these equity-method investments using an income approach based on expected future cash flows and appropriate discount rates. The determination of estimated future cash flows involved significant assumptions regarding gathering volumes and related capital spending. Discount rates utilized ranged from 13.0 percent to 13.3 percent and reflected increases in our estimated cost of capital, revised estimates of expected future cash flows, and risks associated with the underlying businesses.